broadband_amplifier_assignment - ECE194J/594J PS 3 Above is...

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1 cbi C bb R be C ' ' e b m V g be R ex R + - ' ' e b V cbx C ECE194J/594J PS 3. f m depl be be g C C τ + = , Above is a device model . Recall that . Let us take Cje=5.67 fF, beta=50, Ccbi=1.86 fF, Ccbx=1.34 fF, Rbb=14.7 Ohms, Rex=8 Ohms, and tau_f=0.244 ps. Lets use this device model in circuit calculations below. nKT qI g m / = , where n=1.0. This is the model of a transistor having Ae=0.25 um x 4.0 um emitter area and biased at 1 mA/micron current density (4 mA total); the ft is 470 GHz ft and the fmax 825 GHz. It operates at a maximum of 2.5 mA/um at Vce=1.0 volts. In the hand analysis ONLY (for problems 1 and 2), we will simplify by making Ccbi=(1.86+1.34) fF/micron*Le, and making Ccbx=0 Ree Rcs Ree RL RL RL RL Please be very careful in the boundary conditions of the simulation to ensure that Problem 1: The circuit to the left is one stage in a string of identical differential stages. The positive supply is zero volts and the negative supply is -4.2 volts. Use the device model above, but scale the device area--and hence the model element values-- so that all the DC bias voltage drops across RL are 150 mA and the transistors are biased at 1 mA/micron current density. Note critically in this analysis that the load of each stage is RL/2 because of the input impedance of the input impedance of the cascaded stage. (this will determine Rcs, Ree). note that because we are dealing with a

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broadband_amplifier_assignment - ECE194J/594J PS 3 Above is...

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